1. Technical Field
The present invention relates to a magnetic field measurement apparatus using light.
2. Related Art
Some magnetic field measurement apparatus using light measure a very weak magnetic field, such as a magnetic field from the heart (magnetocardiogram) and a magnetic field from the brain (magnetoencephalogram), and are expected to be applied, for example, to medical image diagnosis apparatus. To measure a very weak magnetic field, it is necessary to remove influence of earth magnetism and other magnetic noise. JP-A-2009-162554 describes an atomic magnetism sensor that allows high-sensitivity measurement of a magnetic field gradient by converting a difference in magnetic field intensity between different measurement positions into a difference in the angle of rotation of polarization of laser light for probing linearly polarized light.
The atomic magnetism sensor described in JP-A-2009-162554, however, cannot remove optical noise produced when light is exposed, for example, to sound or heat and contained in the light.